Telephone system



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Jan. 28, 1941. 'r-` F. cRocKER TELEHONE SYSTEM 15 sheets-sheet 15 Filed Nav, 16, 1959 i li() Patented Jan. 2.8, 1941 UNITI-:o srares @TENT OFFICE sociated Electric Laboratories, Inc.,

Chicago,

Ill., a corporation `of Delaware .application November i6, 1939, Serial No. 30455778 73 Claims.

The present invention relates to telephone systems and more particularly to improved automatic switching apparatus of the character of that disclosed and claimed'in U. Si. Patent No. 2,3. 7,710, Thomas `E'. Crocker, issued August 1, 1939, which apparatus isconnected and arranged to handle switchboard traiiic.

A telehpone system of this character conventionally comprises an automatic central office, a number of distant exchanges oi any desired type, and interconnecting toll lines, the central ofce and each of the distant exchanges serving local subscriber substations having subscriberlines eX- tending thereto. Local calls inthe central oiiice and 'in the distant exchanges of the automatic `type are completed under the control of the subscriber `at the `subscriber substations; local calls in other of the distant exchangesare completed inany suitable manner; and calls between the central oiice and the distantiexchanges are completed by operators ata switchboard provided in the centraloflice. Moreiparticularly, theswitchlboard which is provided in the-central cnice comprises a number of operator positions including `groups of inward or toll operator positions, groups of combined line and `recording or C. L. R. operator positions, and groups of delayed or'point- `to-point operator positions.

In handlingr traffic at the switchboard,incoming calls from :the distant exchangestare iirstirouted `by way'of the toll lines to the toll operator positions at the switchboard and then completed therefrom directly to the local subscriber substations inithe central oiiice, or transferred therefrom to the `point-to-point operator positions to be` completed later. Also, through `calls between `the distant exchanges and including the central office are iirst routed by way ofthe toll lines to the` toll operator positions at the switchboard and then extended therefrom by way of the toll lines to `others of the distant exchanges. `Outgoing calls originating at the subscriber substations in the central cnice which are to be extended to distant exchanges are first routed by way of C. L. R. trunks to the C. L. R. operator positions atrthe switchboard and `then completed therefrom `directly by Way of the toll lines to the distant exchanges, orvtransferred therefrom to the point-to-point operator positions to be Completed later. In completing a call from a point-topoint operator position, the operator thereat nrst completes a connectiontothecalled toll line or subscriber substation and-then completes a connection to the calling toll line or subscriber substation.

is `provided `for performing `the variousfunctions over the different toll, trunk and subscriber lines.

it is an object of the present invention to provideiin a ytelephone system of the character described and `including an automatic switch train associated with an operator. position and a trunk accessible to the switch train, an improved trunk circuit associated with the trunk which is so connected and arranged that a connection to the operator position including .the `trunk vmay be `readily controlled and supervised.

Another object of the invention is to` provide in a telephone system of the character described including a paystation, an operator position, a trunk, and switching apparatus for extending a connection from the paystation by .wayof .the trunk to the operator` position, an improvedtrunk circuit associatedwith the trunk which is` so connected and arranged that a connection routed from the paystationby way ofthe switching4 apparatus and the trunk tothe operatorposition and the coin control4 apparatus at thepaystation Vmay be readily governed and supervised.

Another objectof the invention is toprovide in a telephone system of the character described and comprising a central ofdceincluding aswitchboard provided with a number of operatoriposi- Ations and a community automaticexchange ,or fC. A. X. network 'including a. number of exchanges and a number oftoll linesextending therebe- -tweern an improvedarrangement forA completing reverting calls between theuexohanges ,in the C. A. X. network by way, of the tclllin'esfrom Athe operator positions.

Another object ofthe. invention is to provide in a'signaling system includingautomatic switching -mechanism having-access to a plurality `of groups ,of lines, an improved call distributorfor `causing the calling lines in the groups to beseizedby `the `.switching mechanism in a predetermined order.

Another object of the invention is to provide in a signaling system including automatic switching `mechanism having to a plurality oigroups .1,

of lines,l an improved call distributor which is operative through a cycle in order to cause the switching mechanism to seize the calling lines in the groups in a predetermined order, whereby all of the calling lines in a given group are seized one by one by the switching mechanism before any of the calling lines in the succeeding group are seized one by one by the switching mechanism.

Another object of the invention is to provide in a signaling system including automatic switching mechanism having access to a plurality of groups of lines, an improved call distributor which is selectively operative in a plurality of different manners in order to cause calling lines in the groups to be seized by the switching mechanism in a corresponding plurality of different predetermined orders.

A further object of the invention is to provide in a telephone system of the character described including a number of operator positions, an improved call distributor which is so connected and arranged that calls on the lines in the groups are routed group by group in a predetermined order to the operator positions to be answered.

A further object of the invention is to provide in a telephone system of the character described and including a number of universal operator positions and a call distributor for routing incoming toll and trunk calls to the operator positions to be answered, operator controlled means at each of the operator positions for restricting the operation of the call distributor to that of incoming toll calls to the associated operator position to be answered.

A further object of the invention is to provide -in a telephone system of the character described and including a number of universal operator positions and a call distributor for routing inmatic exchange or C. A. X. network including a number of exchanges of the automatic type, and a distant exchange of any suitable type.

The central oiiice serves a number of local subscriber substations and a number of local paystations of the prepay manual type; while the distant exchange .and each of the exchanges in the C. A. X. network serve a number of local subscriber substations. Local switch trains are provided in the central office and in each of the exchanges in the C. A. X. network, thereby to permit the local subscribers in the respective exchanges to complete local calls; while local calls in the distant exchange are completed in any desired manner.

The C. A. X. network includes a tandem exchange and another exchange. Trunk lines are arranged between the other exchange and the tandem exchange in the C. A. X. network; C. A. X. toll lines are arranged between the tandem exchange in the C. A. X. network and the central oilce; while other toll lines are arranged between the distant exchange and the central oiiice. Also, C. L. R. trunks are arranged in the central office which are accessible to the local switch train therein.

A switchboard is arranged in the central ofce which comprises a number of operator positions. Furthermore, a toll switch train is arranged in the central oice which comprises a number of delayed toll selector switches and a number of groups of finder-selector links individually associated with the operator positions at the switchboard, each of the finder-selector links including a link finder switch and a toll selector switch. Each of the link finder switches has access toeach of the delayed toll selector switches, to each of the C. L. R. trunks, to each of the paystation lines, and to each of the toll lines; while each of the toll selector switches and each of the delayed toll selector switches has access to each of the toll lines, and to a number oi toll transmission selector switches. The local switch train comprises a number of finder-selector links, each including a finder switch and a selector switch,

a number of connector switches accessible to the selector switches, and a number of combination local and toll connector switches accessible to the selector switches and to the toll transmission selector switches. Finally, the combination local and toll connector switches and the connector switches have access to the local subscriber lines and to the local paystation lines.

Also, apparatus is arranged at each of the operator positions for governing the operation of the nder-selecton links associated therewith, thereby to answer, to extend, to initiate and to supervise calls routed by way of the associated nder-selector links.

In `accordance with one feature o the invention, each toll line extending between the central oflice and the distant exchange comprises rst and second branches, each branch including two line conductors, and is provided with an associated toll circuit including a ring relay, an order relay and an identity relay. A rst operating circuit is provided for the ring relay which includes one of the line conductors of the second branch of the toll line; a second operating circuit is provided for the order relay which includes the one line conductor of the second branch of the toll line; and a third operating circuit is provided for the identity relay which includes the other line conductor of the second branch of the toll line. Further, the toll circuit comprises a source of ringing voltage, a source of out-of-order voltage, and an identity signal individual to the toll line. The ring relay, the order relay and the identity relay are so connected and arranged that the ring relay is operative to disconnect the first and second branches of the toll line and to connect the source of ringing voltage to the line conduc,

order relay is operative to connect the source oi out-of-order voltage to both branches of the toll line, and that the identity relay is operative to cause operation of the identity signal and to interrupt the rst operating circuit and to complete the second operating circuit in the event it is prepared. The finder switch of any one of the finder-selector links associated with any one of the operator positions is operative to seize the second branch of the toll line, thereby to complete a connection between the one operator position and the toll line. Finally, a device is provided at the one operator position which is selectively operative to complete by way of the nder switch of the one finder-selector link the rst F operating circuit, or to prepare by way of the finder switch of the one finder-selector link the second operating circuit and to complete by way of the nder switch of the one under-selector link the third operating circuit, or to complete finder switch ,having access to each of the paystation lines. Also, an arrangement is provided which fis responsive to the presence of a call on. any one of the paystation lines for causing the nder switch to seize the paystation line, thereyby to complete a connection between the paystation associated with the one paystation line and the trunk circuit. Further, the trunk circuitzcomprises means operative to create a call on the trunk `which is governed by the deposit of a `coin at the paystation. Each of the op- Jerator .positions comprises `apparatus which is operative to `answer a call on the trunk and a device which is selectively operative to cause the `-coin deposited at the paystation to be collected or refunded. Furthermore, means is provided at the :paystation for performing a release operation; and means is provided at the operator position for performing a release operation. Finally, the trunk circuit comprises means controlled by the performance of the release operations yfor causing the release of the finder switch when there is no deposited coin at the paystation and for causing the finder switch to remain operated `and another call to be crea-ted on the trunk when there is atdepesited coin at the paystation.

In accordance with another feature of the invention, the C. A. network comprises two automatic exchanges connected by trunk lines and is so connected and arranged that the subscribers in the two `automatic exchanges may complete vlocal automatic connections in the respective exchanges but are restricted from completing interexchange calls. Also, the C. A. X. network comprises a repeater and means operative to seize the repeater in response to the initiation of an inter-exchange call on a subscriber line in either one of the exchanges, thereby to cause the repeater to seize an idle one of the toll lines eX- `tending between the C. A. X. network and the central office. Means is provided which is controlled `when the one toll line is seized bythe repeater for rendering busy the one toll line and for creating a call on the one toll line. The automatic switching apparatus associated with any one of the opera-tor positions at the switchboard in the central office is operative to seize the one toll line `having a call thereon, thereby to complete a connection between the one operator position and the one toll line. Finally, means is provided which is under the control of the operator `at the one operator position for revertively eX- tending the connection over the switching apparatus and the one toll line to a subscriber line in either one of the exchanges in the C. A. X. network.

In accordance with a further feature of the invention, the telephone system comprises a plurality of groups of lines, switching mechanism having access to the lines in the groups, means for causing `the switching mechanism to seize a calling line in a marked one of the groups, and a call distributor operative to mark; in a predetermined order each one of the groups including a calling line. The call distributor is so connected and arranged that it is operative to markonly one ,of the groups at a time to mark a second oi :the groups only Awhen all ci the calling lines in a marked iirst of the groups have been seized by the switching mechanism. Also, there is provided means controlled by the presence of a, calling line inany `one .of the groups for initiating operation of the call distributor and means controlled when all o'f 'the calling lines in the groups havebeen seized by the switching mechanism for arresting operation ofthe call distributor.

In accordance with a further feature of the invention, the call distributor is operative to mark group by group in accordance with an` established order of preference among the groups each one of the groups including a calling line; and control means is provided which is selectively operative to establish a iixed order of preference among the groups and to establish a variable order of preference among the groups.

In accordance with a further feature of the invention, the telephone system comprises `an excha-nge provided with a switch-board including a plurality of operator positions, a number of groups of 'lines associated with the switchboard, apparatus at each of the operator positions for answering incoming calls on the lines in the groups, a position distributor operative to select in a predetermined order the operator positions,

means for controlling the operation of the position distributor, a call distributor operative to route group by group in a predetermined order incoming calls on the lines in the groups .to select ones of the operator positions, and means for controlling the operation of the call distributor. The call distributor is so connected and arranged that all incoming calls on the lines in a given group are routed one by one to select ones of the operator positions before any incoming calls on lines in a succeeding group are routed one by one to select ones of the operator positions.

In accordance with a further feature of the invention, the call distributor is normally operative to cause a prepared one of the lnder-selector links in a selected one of the groups associated with one of the operator positions to operate and route both toll calls and trunk calls to the one operator position to be answered. Operator controlled means is provided at the one operator position for restricting the operation of the call distributor, whereby only toll calls are routed thereby to the one operator position` to be answered. Additional operator controlled means is provided at the one operator position for preventing the position distributor from selecting any one of the finder-selector links in the associated group when a delayed call is initiated at the one operator position.

Further features of the invention pertain to the particular arrangement of the circuit elements of the system, whereby the above-outlined and additional operating features are attained.

The novel features believed to be characterisl tic of the `invention are set forth with particularity in the appended claims. The invention, both as to its organization and method of operation, together with further objects and advantages thereof, will best be understood by reference to the following specication taken in connection with the accompanying drawings, in which Figure l illustrates the general arrangement of a telephone system embodying the present invention; Figs. 1 to lli, inclusive, taken together, illustrate the details of a system having incorporated therein the features ofthe invention as briefly outlined above; and Fig 16 illustrates the mode of conibiningFigs. 1 to le, inclusive, to form a uniiied system.

CII

Des'crz'ption of the apparatus incorporated in the telephone system Referring now more particularly to Fig. l5 of the drawings, the telephone system there illustrated comprises a central office A, a distant exchange B, a distant community automatic exchange or C. A. X. network including a tandem exchange C and an exchange D associated therewith. The central oce A and each of the exchanges B, C and D serve a number of local stations, the local stations served by the central ofrice A including both subscriber stations and paystations. More particularly, the central oftlce A serves a number of local subscriber substations, including the subscriber substation indicated at T| and associated with the subscriber line extending to the central oflice, and a number of paystations, including the playstation indicated at T2 and associated with the paystation line 296 extending' to the central oflice, each of the paystations being of the prepay manual type; while the tandem exchange C serves a number of subscriber substations, including the subscriber substation indicated at T3 and associated with the subscriber line 955 extending to the tandem exchange. The central oilce A and the distant exchange B are interconnected by a group of twoway toll lines of the ring-down type, including the toll line indicated at |90. The central o'lce A and the tandem exchange C are interconnected by a group of two-way toll lines, including the toll line indicated at 94|). The tandem exchange C is interconnected with the exchange D by a group of two-way trunks, including the trunk indicated at 923. Each of the toll lines extending between the central office A and the distant exchange B terminates in a ring-down toll circuit individual thereto, the ring-down toll circuit lill) being individual to the toll line |55. Each of the toll lines extending between the central office A and the tandem exchange C terminates in a reverting dial toll circuit individual thereto, the reverting dial toll circuit 350 being individual to the toll line 945. Each of the subscriber and paystation lines extending to the central oice A is provided with a line circuit individual thereto, the subscriber line 45| being provided with a line circuit 452 individual thereto, and the paystation line 25B being provided with a line circuit 2235 individual thereto.

The central oiice A and each of the exchanges C and D are of the automatic type, while the distant exchange B may be of any desired type. Accor-dingly, the central office A and each of the exchanges C and D are provided with local switch trains which preferably comprise a plurality of groups of finder, selector and connector switches of the Strowger type arranged in the usual manner in order to set up the various connections between the local subscriber substations in the central oiiice A and in the exchanges C and D. More particularly, the central office A is provided with a local switch train comprising a number of local links, including the local link 454, and a number of connector switches, including the connector switch 465. Each of the local links comprises a finder switch and a selector switch, the local link 454 comprising a finder switch 456 and a selector switch 455. Preferably, the finder switches, the selector switches and the connector switches in the local switch train are of the Strowger type and are connected and arranged in a well known manner.

Also, a group of combined line and recording or C. L. R. trunks, including the C. L. R. trunk 450, is provided in the central oce A, which trunks are accessible to the selector switches of the local switch train. More particularly, the C. L. R. trunk 450 is accessible to the selector switch 455 of the local link 454. Furthermore, `a C. L. R. trunk circuit is individually associated with each C. L. R. trunk, the C. L. R. trunk circuit 455 being individually associated with the C. L. R. trunk 450.

Further, the central oiiice A is provided with a toll switch train comprising a plurality of groups of under-selector links, one of the groups including the link illustrated which comprises the finder switch 155 and the toll selector switch 80D; a group of delayed toll selector switches, including the delayed toll selector switch 446; a group of toll transmission selector switches, including the toll transmission selector switch 513; and a group of combination local and toll connector switches, including the combination local and toll connector switch 514. Preferably, these switches are of the Strowger type and are ccnnected and arranged in a manner more fully described subsequently.

An automatic dial switchboard is arranged in the central ofce A and comprises a number of operator positions, each operator position having a group of finder-selector links individually associated therewith. For example, the finder-selector link illustrated is included in a group of links individually associated with the first oper- -ator position |400 at the switchboard.

Each of the nder switches of the nder-selector links) has access to each of the C. L. R. trunks in the central ofce A, to each of the C. A. X. toll lines extending between the central cnice A and the tandem exchange C, to each of the toll lines extending between the central ofce A and the distant exchange B, to each delayed toll selector switch and to each of the paystation lines in the central oice A. More specifically, the noler switch 15G of the under-selector link illustrated has access to the C. L. R. trunk 45H by way of the trunk line 445, to the C. A. X. toll line 945 by way of the trunk line 3H), to the toll line I9@ by way of the trunk line |80, to the delayed toll selector switch 445 by way of the trunk line 445, and to the paystation line 290 by way of the trunk line 285. Furthermore, the nnder switch 'E05 is accessible to the trunk circuit at the rst operator position |400 by way of the cable i210. Also, each of the toll selector switches and each of the delayed toll selector switches has access to each of the toll lines extending between the central ofce A and the distant exchange B, to each of the C. A. X. toll lines, and to a group of toll transmission selector switches.' More speciiically, the delayed toll selector switch 445 andl the toll selector switch 800 each has access to the toll line |90 by way of the trunk line |10, to the C. A. X. toll line 940 by way of the trunk line 340, and to the toll transmission selector switch 513 by way of the trunk line 585.

Also, it is noted that a toll train trunk circuit is provided with each individual toll transmission selector switch and is interposed between the toll transmission selector switch and the delayed toll selector switches and the toll selector switches. More particularly, the toll train trunk circuit 55E! is individually provided with the toll transmission selector switch 513 and is directly connected to the trunk line 580.

Each of the combination local and toll conl to the vai line terminating at. the` central cnice A.V More particularly, the combination local and toll con-.l

nector switch tilt isI accessible to the selector switches in the local switch train bywayof the line niet and is accessible to the tolltransmi'ssion selector switches by way of the line. l5; Also, the selector` switches in the localV switch train have access to the group of C. L..R. trunks at the central ofice A and to the group of connector switches in the local switch train; while the connector switches in the local switch train have accesstoeaeh subscriberline and-each paystationr line terminating. at the, central office A. Also, it is noted that a group: of prepay manual trunk circuits is provided in the central cnice A and interposed between the; individual trunk' linesextending to the finder switches of thai-lnder-selector links associated with the operator positions at the switchboard' and.. the various paystationr lines, this` group` of prepay manual l trunk. circuits including. the prepay manual trunk switchboard in. the central oflice A, is of the univerbal" type, thereby making itpossible.y to render toll, C.4 L. point-to-point. service at each operator* position. Also, at least: the first and second' operator positions are so connected and ngcd that the service rendered thereby may be restricted to toll service. Also, the` central cnice A comprises' a common start and level distributor unit l'llllll, which is arranged to distributeto the Ender switches of the linksassociated with the operator positions in a manner more .fully described hereinafter, and' a. position distributor telit, which` is so connected and arranged that incoming calls to the switchboard rented in a predetermined order tothe operpositions to be` answered.

More particularly, the common start and level distributor unit itil@ is so connected and arranged' that; the differ-ent types of trunk calls and the: d qu'ent types ofiV toll calls are routed` lusJ operator: positions to be answered in a. predetermined order. The comm-on start and. levelA distributor unit` ltlllloperates to; route all calls er a partieulartype, either trunk or toll, to thevarious operator positions tov beanswered e any calls-oi another type, either trunk or toll, are` routed. to the various operator positions to be answered; the type ci calls answered rst determined by the type.y of, call` rst in- ^g the switchboard. This arrangement that all, of the calls of a given type are .weredi beioreany. of the calls. of. another type answered.

Also individually associated with. each operator position are one or moresender control circuits, the sender control circuit 451i.: being individually associated with. the iirst operator position Mtl). Furthermore; at each operator position there is provided a sending key set. individual thereto which is associated witheach of thesender control circuits associated with the operator position, the: sending key set i'tlbeing individually associated with the iirst operator .position lllllll and with the sender control circuit 451. Finally, a grouptoi digit register-andi con-trol circuits is commonly associated with the switchboard, each of the sender control circuits being provided with` switching apparatus having access to each ofthe digit register and control circuits and being operative .to select an idle digit register and control circuit when the sender control circuit is taken for use. Also, each of the sender control circuits is provided with switching apparatus having access to the trunk circuit at the operator position individual thereto and to each of the under-selector links individually associated with the associated operator position. More specically, the sender control circuit fidi is. individually associated with the iirst operator position. lllillll by way of the line it and is operatively associated with the sending key set 463 by way of the line 46S. Also, the sender control circuit ttl hasaccess Kto the digit register `and control circuit iti by'way of the line llill tothe trunk circuit at the first operator position by way of the cable litt and to the toll selector switch llllll of the finder-selector link illustrated by way of the cable '136.

Preferably, the elements of the C. A. X; network, 4as best shown in Fig. 9, are connected and arranged in the manner described and claimed in U.` S. Patent No. 2;133,682, Pier Bakker, issued October 18, 1938; Brieiiy, the C. A. X. network comprises a tandem exchange C andan exchange D interconnected by a group of trunk lines including the trunk line 92d. Individually associated with each of the trunk lines extending between the tandem exchange C. and the exchange D are a line circuit and a line switch, the line circuit 92| and the line switch Still being individually associated with the trunk line 92o. Also arranged in the exchange D is a local switch train w-hichzs utilized in completing locall calls therein. Each of the C. A. X. toll lines extending between the central oiiice A and theI tandem exchange C is provided with a line circuit individual thereto, the-line circuit 932 being individual to the C; A. X. toll line 940.

A number of subscriber lines, including. the subscriber line Qllll, are served vby the tandem exchange C. Each; subscriber line has a subscriber substation and a line switch individually associated therewith, the subscriberA substation T3 and theline switch Selll being individually associated with the subscriber line toil. A switch train is provided in the tandem exchange C which comprises agroup of local rst selectorswitches, including the local first selector switch. 9M, a group of' incoming rst selector switches, including the incoming first selector switch Sl 2, a group oi dial back selector switches, including the dial back selector switch Slll; a group` of local and toll connector switches, including the local and toll connector switch llill, and a group of dial back repeaters, including the dial vback repeater SIS. Each of the-dial back repeaters is provided with a line switch individual thereto, the line switch S9 lll being individual to the dial `back repeater 9 lli.

Further, it is noted that the incoming first selector switches are individually associated with the lin-e circuits of the C. A. X. toll lines extending between the central oice A and the .tandem exchange C, the incoming first seleotorswitch 9 l2 being individually associated by way of the line 943 with the line circuit 32 of the C. A. X. toll line 94u; while the dial back selector switches are individually associated with the dial back repeat'- ers, .the dial back selector switch llll being individually associated by way of the line 9H with the dial back repeater 9l6.

The switch train provided in the tandem exchange C is so connected and arranged that the 

